American X-Planes

Research Project

1. Introduction:

1.1 The objective in this research project is to make inform my audience about the different technologies tested in X-planes and about the various reasons of the X-program failures and why these crafts are not brought into production.

1.2 The hypothesis of this project would find out why only two X- crafts made significant contributions to the modern aviation industry (X-32 and X-35).

1.3 The thesis statement would be: There were various causes of failures of the X-projects and only one of these crafts made it to full scale production (X-35).

1.4 The boundaries of this project have been limited to few, key technological contributions by these aircrafts and those only those specifications which have been disclosed by US government and Department of Defense.

2. Methodology:

This research paper has been conducted over a period of eight weeks and various resources have been used during this while. The main source used was NASA's online forum through which access was available to Jenkins, Landis and Miller's summary on this topic. Along with the internet I also browsed through a few books on aviation which were available at the Dubai Public Library and referenced aviation magazines and articles which I got a hold of from the college library. Other sources included few websites, including Wikipedia.

3. Findings:

3.1 Background:

The X-planes are a series of specially built experimental United States aircraft (and some rockets) used for testing of new technologies and usually kept highly secret during development.

The first of these, the Bell X-1, became well-known as the first plane to break the sound barrier. As of 2006, new X-plane projects are still underway. Till date, 52 X-planes have been built (the designation X-52 was skipped and moved on to X-53 to avoid confusion with the B-52 bomber).

3.2 The Failures:

The X-series had a range of failures over the past half decade.

Lack of technological availability,

In-flight explosions,

Inertia-coupling,

Lack of funding,

Ineffective design,

Engine failures,

Risk of having on-board nuclear capability,

Non-productive test-career.

3.3 The Significant Ones:

3.3.1 The X-1 was the first aircraft ever to break the sound barrier. It was designed to fly at double the speed of sound and set altitude records in excess of 90,000 feet. Hence, Chuck Yeager became the first man ever to cross Mach 1 (Miller 2001).

3.3.2 The X-11 and X-12 series were Consolidated-Vultee Aircrafts. They successfully demonstrated the pressure-stabilized propellant tanks and propulsion system components destined to equip the Atlas ICBM-- which later became one of the premier space launch vehicles (Jenkins, Landis and Miller 2003).

3.3.3 The X-14 successfully demonstrated that the concept of vectored jet thrust was viable, as subsequently used on the BAe/McDonnell Douglas Harrier. It continued flying for nearly a quarter century before being retired to the Army Aviation Museum (Jenkins, Landis and Miller 2003).

3.3.4 The X-15 was constructed specifically to explore the hypersonic (Mach 5+) flight regime, along with the necessary structures, propulsion systems, and control techniques. Although it was discontinued from tests because one crashed while returning from space--killing test pilot Major Michael J. Adams (Godwin ed 2001).

3.3.5 The X-17 program proved to be one of the most successful of the 1950s and of the fastest of the X series. Dues to extreme testing conditions no living model survives (Jenkins, Landis and Miller 2003).

3.3.6 The X-24 decisively demonstrated that lifting-bodies could consistently make precision landings onto a hard runway, proving the concept for the future Space Shuttle. When the X-24 completed its final flight in September 1975, it marked the end of rocket-powered research aircraft at Edwards--at least for 25 years. The X-24B is currently on display at the Air Force Museum (Reed 2002).

3.3.7 The X-31 was designed to break the "stall barrier," allowing it to flight at angles of attack which would typically cause an aircraft to stall with a complete loss of control. Two X-31s were built for carrying out this purpose. The first X-31 was lost in January 1995--the pilot, Karl Lang, ejected safely at 18,000 feet before the aircraft crashed. The second completed the 580th and last flight of its original research program in May 1995 and was placed in storage. The X-31 was later taken to the air again in May 2002. (Langevin, Overbey 2003)

3.3.8 The X-33 was designed to demonstrate unique aero-spike engines, composite liquid hydrogen tanks, and a metallic thermal protection system. The development program ran into problems almost immediately, and the failure of the composite liquid hydrogen tanks during full-scale testing led to massive cost overruns. As a result, NASA cancelled further funding for the X-33 in March 2001 after the vehicle was about 75 percent complete. This left Lockheed, who had already invested over $200 million of company funds in the project, free to complete and fly the X-33 alone, but the company elected not to do so (Jenkins, Landis and Miller, 2003).

3.3.9 The X-37, still in the developmental phase and formerly known as the Future-X Pathfinder, will make a series of atmospheric and orbital test flights to evaluate over 40 airframe, propulsion, and operations technologies designed to lower the cost of access to space. The X-37 flights will permit testing of a wide variety of experiments and technologies to be evaluated under real-world conditions. The vehicle design also includes a small experiment bay to allow subsystem testing during the reentry flights (Jenkins, Landis and Miller, 2003).

3.3.10 The X-39 designator was planned under the Future Aircraft Technology Enhancements (FATE) program. FATE was intended to develop revolutionary technologies that would become the foundation for next generation of combat